It's actually the law in Iran for women to cover, not just a custom. Which really does create a cleft stick: don't deal with the country at all; give all the jobs to the boys; or break the law of the country.
The Swedes have been getting on and dealing with Iran while not breaking the law of Iran when actually in that country; it's likely they deal with the US in exactly the same way, ie not breaking the law of the US when in that country - even if they disagree with laws in both.
I'm not keen on them being legally forced to wear the hijab, and its possible the Swedish women may well not have been either. But I note the male writer puts words in the women's mouths, rather than asking what they actually said to the Iranians.
Oh, and the article is factually wrong:
"On the one hand you have an American President and former Miss Universe competition owner who has done nothing to diminish women’s rights."
Doesn't sound like an accurate description of a man who has described how he personally sexually assaults women by grabbing them by the pussy. And there are multiple outstanding allegations of sexual assault against him.